Travelling Light, By Tove Jansson, trans. Silvester Mazzarella

It was just exactly as she had imagined it, a great silken-smooth life-force caught and held in her hands. To her astonishment, the rare, furious joy of clasping the creature in her arms suddenly went right through her and took her breath away." The creature is a huge, friendly, importunate herring-gull, whom the woman, Elsa, has named Casimir. She and her husband Arne have come to a remote island to help him get over a breakdown induced by teaching unruly classes. The seabirds will be their solace and diversion. But though there are generic truths about these sharers of their island for the couple to perceive, there are particular ones also – and Casimir remains Casimir, with unique demands.

Such a realisation is at the heart of "The Gulls", and at the heart too of Tove Jansson's art as a whole, nowhere more subtly and distinctively than in this superb collection of 12 short stories. In "The Summer Child", again set on an island, the Fredriksons have their holiday all but ruined by a young guest whom they have invited to stay "out of the goodness of their hearts, and for a small fee, of course". Elis has no diffidence about criticising his hosts to their faces - for their indifference (as he sees it) to the grave problems of the world, or to suffering as a fact of existence. But just as we are tempted to categorise the boy psychologically, Jansson, in a sequence with the visual immediacy of film, isolates him and the host family's son, Tom on an islet upon which stands a lighthouse.

Out here the pair elicit from each other responses revealing qualities their personas have inhibited them from expressing. Hopkins's "There lives the dearest freshness deep down things" could be the motto for this, and every other story here.

Solitary protagonists, bewildered yet possessed of reserves of strength, constitute some of this book's most haunting figures. The old man in "A Foreign City" has forgotten the name of the hotel where he should spend the night on his stopover. In possession of a hat returned to him by Customs instead of his own missing one, he looks at the address written in its lining and decides instead to take a taxi there. The professor of Nordic literature in "The Garden of Eden" arrives at a Spanish village and sees it ecstatically – and she is to persist in her vision throughout confrontations with warring expats.

Jansson's famous Moomin stories for children gave us beings arising out of intimately rendered Finnish landscapes in changing seasons. The fine novels she wrote later in her life (1914-2001) – The True Deceiver is surely a masterpiece – counterpoint intricacies of emotion and behaviour with assertions of nature. Swedish-speaking Finland, both rural and urban, is a constant presence in Travelling Light too. Yet perhaps its most disturbing, beautifully wrought story is set in France. In "The PE Teacher's Death", a suicide disrupts the colour-supplement lifestyle of its characters. This volume has an indispensable, thoughtful introduction by Ali Smith and has been translated by Silvester Mazzarella into limpid, sensitive prose.